Approximately 80 percent of women who underwent prophylactic mastectomy did not have clinical indications that would classify them as high risk for recurrence. In the subgroup of patients without clinical indications, concern about cancer recurrence figured more prominently in the decision to have a prophylactic contralateral mastectomy, as compared with patients who did have clinical indications.

Women who underwent mastectomy for the primary cancer were almost three times as likely to have the prophylactic procedure compared with the overall group of patients, according to Dr. Sarah Hawley of the University of Michigan in Ann Arbor.

"Clinical indications for developing a new primary breast cancer -- that is, a positive genetic test and/or strong family history -- were significantly associated with receipt of contralateral prophylactic mastectomy," Hawley said during a press briefing prior to the Quality Care Symposium in San Diego. "However, many women who received contralateral prophylactic mastectomy did not have a clinical indication.

"Worry about recurrence had a strong influence on receipt of contralateral prophylactic mastectomy, although this procedure has not been associated with reducing recurrence risk," Hawley added.

Several studies have documented a rise in the frequency of contralateral prophylactic mastectomy among breast cancer patients, despite the fact that few women have clinical indications for the procedure. Patient misconceptions about recurrence risk have been implicated in the increase in prophylactic procedures.

In the absence of data to explain the increase, concern has arisen about the potential for overtreatment, particularly given the relative rarity -- about 1 percent -- of contralateral disease as a site of recurrence. In an effort to inform on the issue, Hawley and colleagues surveyed 2,245 women from the Detroit and Los Angeles registries of the NCI's Surveillance, Epidemiology, and End Results (SEER) program.

The women were first surveyed following breast cancer diagnosis during 2005 to 2007. Four years later, investigators repeated the survey with 1,525 of the original participants.

Of 1,446 women who were recurrence free at follow-up, 35 percent said they had considered contralateral prophylactic mastectomy, and 7 percent of the patients had opted for removal of the disease-free opposite breast. In the subgroup of 564 women who underwent mastectomy for the primary tumor, 53 percent had considered contralateral prophylactic mastectomy, and 19 percent underwent the procedure.

The Society of Surgical Oncology (SSO) recommends consideration of contralateral prophylactic mastectomy for breast cancer patients who have known mutations in BRCA1 or BRCA2 or who have a family history of breast cancer involving multiple first-degree relatives, Hawley noted. Among women who chose to have a contralateral prophylactic mastectomy, about 80 percent did not meet the either of the SSO criteria.

a strong family history of breast cancer or a positive test for a breast cancer-associated gene mutation significantly influenced the decision to undergo contralateral prophylactic mastectomy, according to the study. Neither factor influenced the choice of mastectomy versus breast conservation as initial treatment for the primary tumor.

However, women who had negative mutation tests also were significantly more likely to opt for contralateral prophylactic mastectomy, the study found. Worry about the risk of recurrence increased the odds of having any mastectomy by 69 percent and doubled the odds of contralateral prophylactic mastectomy.

Fear Drives Prophylactic Mastectomy

A higher proportion of women who underwent contralateral prophylactic mastectomy acknowledged being "very worried" about recurrence as compared with women who mastectomy only for the primary tumor, according to the study.

"This analysis of the SEER data suggests that we, as physicians, may not be adequately educating our patients about their risk for recurrent disease, " said Dr. Jyoti Patel, a spokesperson for the American Society for Clinical Oncology. "More unfortunately, many women who overestimate the risk of developing breast cancer in the contralateral breast undergo unnecessary surgery."

"This study suggests that we re-examine how we communicate with our patients regarding how we educate our patients about the decision to undergo prophylactic mastectomy," Patel added.

Public interest in prophylactic mastectomy has been piqued by well-publicized announcements by celebrities.

Miss America contestant Allyn Rose, who will represent the District of Columbia in the pageant, announced her intention to undergo bilateral prophylactic mastectomy because of familial cancer risk. Her mother died of breast cancer when Rose was a teenager.

Both cases involved women with clinical indications for prophylactic mastectomy.